A huge blaze at a footwear factory in the Philippine capital Manila has killed 72 people, authorities say, as angry relatives and workers described sweatshop conditions including dismal fire safety standards.

Firefighters and police pulled dozens of corpses out of the ruins of the two-storey building on Thursday, a day after the blaze trapped the terrified workers with apparently few exits and no fire safety training.

“Many of those retrieved were reduced to skulls and bones,” national police chief Leonardo Espina said, as local authorities confirmed 72 people had died.

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“Someone will definitely be charged because of the deaths. It doesn’t matter if it’s an accident, people died. Right now, we are investigating to clearly define what happened. For sure, someone will be charged.”

Sparks from welding equipment used to repair a broken gate are believed to have caused the fire when they ignited flammable chemicals stored nearby.

By early afternoon on Thursday, 72 bodies had been pulled from the gutted building, Valenzuela mayor Rex Gatchalian said.

He said he believed this would be close to the final death toll, as the figure matched the number of people missing.

The building, among a long row of factories in the rundown district of Valenzuela on the northern edge of the Philippine capital, made cheap slippers and sandals for the local market.

The footwear had names such as “Havana” that sound like well-known global brands, company employees said.

The factory workers toiled for below minimum wage while surrounded by foul-smelling chemicals and were not aware of fire safety standards, survivors and relatives said.

One survivor, 23-year-old Lisandro Mendoza, said he escaped by running out the back door, but that the company had not conducted any fire safety education or drills during his five months working there.

Mendoza said he worked 12-hour days, seven days a week, for 3500 pesos ($A97.39), mixing chemicals.

Another survivor, Janet Victoriano, also described lax fire safety standards.

Victoriano said she was able to escape because she was near the front door when the blaze started.

Deadly fires regularly rip through the poor areas of the Philippine capital, but mostly in shanty homes where there are virtually no fire safety standards.

– AAP